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Introduction to SS7 Konrad Hammel Sangoma Technologies.

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Presentation on theme: "Introduction to SS7 Konrad Hammel Sangoma Technologies."— Presentation transcript:

1 Introduction to SS7 Konrad Hammel Sangoma Technologies

2 What is SS7? SS7 Network Elements –SCP, STP, and SSP SS7 Link Types –A,B,C,D,E, and F links Basic Call Messages –IAM, ACM, ANM, REL, and RLC SS7 Signaling Stack –MTP1, MTP2, MTP3, ISUP, and others SS7 Signaling Messages –FISU, LSSU, and MSUs SS7 Addressing –SPC, DPC, and APC Outline 2

3 Signaling System 7 –CCSS7, C7, number 7, CCIS7 Official Standard by ITU in 1980 Common Channel Signaling (CCS) –Signaling channel, CICs 2 versions…ITU and ANSI Universal signaling via a suite of sub-protocols –ISUP, TUP, DUP, etc What is SS7? 3

4 3 types of Switches Signal Switching Points (SSP) –Terminate signaling links –Start, end, and switch calls Signal Transfer Points (STP) –Main routing switches Signal Control Points (SCP) –Switches attached to Databases SS7 Network Elements 4

5 5

6 A Links –Link between to end-points –“A” stands for Access –Purpose is to deliver signaling messages –Connects an SSP to an STP –Connects an SCP to an STP C Link –Link between 2 STPs (making them a “mated” pair) –“C” stands for Cross Link SS7 Link Types 6

7 7

8 B Links –Link between 2 mated STP pairs –“B” stands for Bridge Link D Links –Link between 2 mated STP pairs (different hierarchical levels) –“D” stands for Diagonal Link SS7 Link Types 8

9 9

10 E Links –Link between an SSP and a secondary mated STP –“E” stands for Extended Link F Links –Link between 2 SSPs –“F” stands for Fully Associated SS7 Link Types 10

11 SS7 Link Types 11

12 5 Basic messages to establish a connected between 2 end points IAM –Initial Address Message –Requests the call/connection ACM –Address Complete Message –Confirms reception of IAM ANM –Answer Message –Confirms the route of the voice (which CICs to use) REL –Release Message –Requests an end to the call RLC –Release Complete Message –Confirms the end of the call Basic Call Messages 12

13 MTP1 –Physical layer –DS-0 channel (56k or 64bit) MTP2 –Data Link Layer –Ensures reliable transmission –Error checking, flow control, and sequence checking MTP3 –Network Link Layer –Ensures message delivery in the network –Addressing, routing, and congestion control ISUP –Application Layer –Protocol that establishes calls between 2 end points –Call setup, call information, and call tear down SS7 Signaling Stack 13

14 3 type of messages FISU –Fill In Signal Units –MTP2 –Sequence checking, error checking, and line filler LSSU –Link Status Signal Units –MTP2 –Signaling status messages –Used to “align” or “sync” two points MSU –Message Signal Units –MTP3 –Carry all messages between points SS7 Signaling Messages 14

15 3 types of addresses 2 different styles of addresses –ITU -> Decimal Number…1234 –ANSI -> Network-Cluster-Member…. 1-2-3 SPC –Self Point Code –The address of the local system APC –Adjacent Point Code –Address of system on the other end of the signaling link DPC –Destination Point Code –Address of system that controls the voice CICs SS7 Addressing 15

16 THANK YOU. 16


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